THE ANNALS 



AND 



MAGAZINE OF NATURAL HLSTORY 



No. 43. MAY 1841. 



XIX. — Oil the Alieraiion which the Atmosphere undergoes 

 during the Developmeiit of Heat in the Spadix q/Colocasia 

 odora. By Professors G. Vrolik and W. H. De Vbiese. 



[Communicated by the Authors.] 



Having communicated last year to the first class of the Royal 

 Institute of the Netherlands our experiments regarding the 

 influence of the spadix of Colocasia odora on the surrounding 

 atmosphere, we have, in repeating the experiments, constantly 

 obtained the same results with the flowers of this species. 

 Thus convinced that our researches have risen in scientific 

 value, we now subjoin the final result of them. 



We used for this experiment the apparatus already de- 

 scribed and delineated*, but we did not employ water for 

 closing the gas jar, but mercury, as was also the case with 

 the experiments communicated last year. 



We placed the flowers in this apparatus, having previously 

 cut away the greatest part of the spatha, and having varnished 

 the remaining part in such a manner that all evaporation or 

 absorption was prevented, and the green surface could not 

 thus exercise any influence. 



We determined the degree of heat in the usual way, but we 

 have not kept our notes on this as fully as before ; it not 

 being now so much the object to make this known, as to con- 

 sider the development of heat, in connexion wdth the alter- 

 ation, which, during it, the atmosphere undergoes. For the 

 same reason no account has been given of all the experiments 

 which we have made. 



July 9th, 1839. — Experiment with a plant planted in the 

 open ground in a hot- house. An idea can scarcely be formed 

 of the vigorous development of the plant treated in this way. 

 Most of the leaves had a petiole of 1*60 Dutch ell (metre) in 

 length. From the union of the petiole with the stem to tiie 

 apex of the middle nerve, the length was 0*66 — 0'80 D. ell ; 



* Tijdschrift voor Nat. Gcsch. en Phys. Deel V., p. lo9, pi. V. — Ann. des 

 Sc. Nat., 2nde Ser., Fevr. 1839. 



Ann. ^ Mag. N. Hist. Vol. vii. M 



